The solar credits multiplier was a temporary boost to the number of certificates a small solar system could earn. It sat on top of the normal calculation, and it explains why early-2010s systems had unusually generous discounts.
How the multiplier worked
Introduced on 9 June 2009 and replacing the Solar Homes and Communities Plan, Solar Credits applied a multiplier to the certificates created for the first 1.5 kW of a small generation unit. Capacity above 1.5 kW earned certificates at the standard rate. A 3 kW system under a 5x multiplier therefore earned the equivalent of 5 times the first 1.5 kW plus 1.5 kW at normal value, not 5 times the whole system.
The schedule
| Period | Multiplier |
|---|---|
| 9 June 2009 to 30 June 2011 | 5x |
| 1 July 2011 to 30 June 2012 | 3x |
| 1 July 2012 to 30 June 2013 | 2x |
| From 1 July 2013 | None |
The multiplier covered both the old RECs and, from 1 January 2011, STCs. It was deliberately stepped down so that the market adjusted gradually as panel prices fell.
Why it ended
Panel prices dropped sharply over those four years, and uptake blew well past early forecasts. The multiplier had done its job, and the scheme’s cost to electricity customers, who ultimately fund certificates through their bills, was rising. Ending it in 2013 let the market run on the deeming period alone.
What replaced it as the lever
Since 2013 the only things that change the certificate count are system size, zone rating and the deeming period. The deeming period began shrinking by one year each year from 2017, which is why the rebate falls every January. See the pillar page on deeming, why the solar rebate drops every year and the wider STC scheme history.
What this means for installers and homeowners
If you see an old quote or a forum post quoting “5 times” credits, ignore it. Work from the current formula: kW times zone rating times deeming years, rounded down. The STC calculator does this for any postcode, and the deeming period and zone ratings resource shows the table. Installers who want the live rate for the certificates should check pricing and how it works.
From the desk: the 5x, 3x and 2x labels are still used in some old STC systems and spreadsheets. Never apply a multiplier to a current installation; the Clean Energy Regulator will reject a claim that does.
Common questions
Did the multiplier apply to the whole system? No, only to the first 1.5 kW. Did it apply to batteries? No; batteries entered the STC system only in 2025. Can I claim it retrospectively? No. The multiplier depended on the installation date, and the claim window for those years has long closed.